Bioenergetics impairment of Trypanosoma cruzi by the antihypertensive manidipine: A drug repurposing strategy.

Considering the lack of effective and safe therapy for the treatment of Chagas disease, the antihypertensive drug manidipine (MDP) was in vitro evaluated against Trypanosoma cruzi. The bioenergetics of trypomastigotes was studied in the presence of the drug using fluorimetric and luminescent assays. Manidipine showed a potent antiparasitic activity, with IC50 values of 0.1 µM (intracellular amastigotes) and 3 µM (trypomastigotes), resulting in a promising selectivity index against the amastigotes (>1459). Using fluorimetric analysis, the drug showed depolarisation of the electric potential of the plasma membrane with no alteration of the permeability. A decrease in ATP levels suggested a bioenergetic alteration of the mitochondria, which was confirmed by the depolarisation of the mitochondrial membrane potential and a slight increase of the ROS levels. This is the first study to show the promising in vitro effectiveness of the antihypertensive MDP against T. cruzi, which may represent a candidate for future investigations in animal models.

Coumaric acid analogues inhibit growth and melanin biosynthesis in Cryptococcus neoformans and potentialize amphotericin B antifungal activity.

Fungal infections are on the rise, since the imunocompromised population is increasing due to AIDS/HIV, organ transplant and chemotherapy. Many environmental and pathogenic fungi are able to accomplish melanin biosynthesis as a virulence factor to promote host invasion. Melanized cells are more resistant to radiation, oxidative and osmotic stresses; also melanin confers an advantage in vivo, since melanized cells are more resistant to phagocytic engulfment and oxidative stress caused by the host defense cells and by some antifungal drugs, such as fluconazole (FCZ) and amphotericin B (AmB). Brown, red or black melanin pigments can be produced by the polyketide pathway (DHN-melanin) or from dihydroxyphenols, such as L-DOPA (L-3,4-dihydroxyphenylalanine) and L-tyrosine by polyphenoloxidases. Among several pathogenic fungi, Cryptococcus neoformans is a melanized yeast that causes pneumonia and meningoencephalitis in immunocompromised patients. The knockout of the laccase genes or other interruptions on melanin biosynthetic pathway generates cryptococcal strains with attenuated virulence in an animal model. In this study 16 analogues of coumaric and cinnamic acid were evaluated as possible tyrosinase inhibitors. We have identified some valuable inhibitors of C. neoformans growth and melanin biosynthesis disruption agents. The results showed that coumaric acid derivatives (1a-c), the ketones (3a-b) and 2-allylphenol (7c) are significant inhibitors of tyrosinase and melanization of the fungus. Two analogues (1b and 3b) were selected as promising antimelanogenic agents to be combined with AmB, showing to promote 16-fold reduction in the AmB fungicidal concentration with no appreciable cytotoxicity to mammalian cells. The data suggest that inhibition of the melanin biosynthesis by these compounds may increase the susceptibility of the cells to the oxidative stress generated by AmB. In summary, our data show that C. neoformans can be a suitable model system to test novel inhibitors that target melanin biosynthesis, and novel compounds for adjunct therapy against C. neoformans were identified.

Mecanismo de Ação do Anti-hipertensivo Manidipino em Trypanosoma cruzi: Uma Abordagem de Reposicionamento de Fármaco / Mechanism of Action of the Antihypertensive Drug Manidipine in Trypanosoma cruzi: A Drug Repositioning Approach

A doença de Chagas (DC), também conhecida como tripanossomíase americana, afeta cerca de 6 a 7 milhões de pessoas em todo o mundo, com aproximadamente 70 milhões de pessoas em áreas de risco. Causada pelo parasita Trypanosoma cruzi, a DC é um problema de saúde pública, ocorrendo do sul dos Estados Unidos ao norte da Argentina. Considerando a falta de terapia eficaz e segura para o tratamento da DC, e baseado em um efeito letal do fármaco anti-hipertensivo manidipino, aprovado pela Food and Drug Administration (FDA), este fármaco foi avaliado in vitro contra as formas tripomastigotas (extracelulares) e amastigotas (intracelulares) de Trypanosoma cruzi. O perfil bioenergético de tripomastigotas de T. cruzi foi estudado na presença do fármaco manidipino, utilizando ensaios fluorimétricos e luminescentes. O manidipino mostrou uma elevada atividade antiparasitária, com valores de CE50 de 0,1 µM em amastigotas intracelulares, e 3 µM em tripomastigotas, resultando em um índice de seletividade em formas amastigotas intracelulares promissor de > 2.000. Utilizando análise por citometria de fluxo, o fármaco mostrou despolarização...(AU)

Chagas Disease (CD), also known as American trypanosomiasis affects about 6 to 7 million people worldwide, with approximately 70 million people in risk areas. Caused by the parasite Trypanosoma cruzi, CD is a public health problem, occurring from the southern United States to northern Argentina. Considering the lack of effective and safe therapy for the treatment of CD, and based on a specific biochemical effect of a approved drug by Food and Drug Administration (FDA), the antihypertensive drug manidipine was in vitro evaluated against the trypomastigotes (extracellular) and intracellular (amastigotes) of Trypanosoma cruzi. The bioenergetics of trypomastigotes was studied in the presence of the drug using fluorimetric and luminescent assays. Manidipine showed a potent antiparasitic activity, with IC50 values of 0.1 µM (intracellular amastigotes) and 3 µM (trypomastigotes), resulting in a promising selectivity index against intracellular amastigotes (>2.000). Using flow cytometry analysis, the drug showed depolarization of electric potential of the plasma membrane, with no alteration of the permeability. A decrease of the ATP levels suggested a bioenergetics alteration of the mitochondria, which was confirmed by depolarization of the mitochondrial membrane potential and increased levels of ROS. The antihypertensive manidipine showed for the first time a promising in vitro effectiveness against T. cruzi and may represent a candidate for future investigations in animal models. (AU)